1. Field of the Invention
The present invention relates to a magnetic recording head, and more particularly, to a perpendicular magnetic recording head having a main pole formed in a roughly trapezoidal shape and a method of manufacturing the same.
2. Description of the Related Art
In general, magnetic recording media are classified into a longitudinal magnetic recording medium and a perpendicular magnetic recording medium based on whether a magnetic polarization of a domain is longitudinal or perpendicular. The perpendicular magnetic medium is proper to increase a recording density. The magnetic recording medium is usually provided in a disk shape and a device of recording data thereon is referred as a magnetic head. Such a perpendicular magnetic recording head includes a main write pole for applying a magnetic field to the magnetic recording medium, and a return pole for allowing the applied magnetic field to return. The perpendicular magnetic recording head has a thin film-laminated structure so as to be miniaturized.
In order to increase the magnetic recording density, a track-width of the disk-shaped magnetic recording medium has to be narrow. To this end, it is important to reduce a width of the main pole. However, the magnetic recording head with the conventional laminated structure has a limitation in reducing the width of the main pole due to the restriction in a patterning technique.
A laminated structure of a conventional magnetic recording head and a method of manufacturing the same will now be described briefly with reference to FIGS. 1 through 3. FIG. 1 is a schematic view illustrating a relationship between a trapezoidal main pole and a track width in the prior art. A main pole 10 has a roughly trapezoidal shape when viewing perpendicularly from a recording surface of the magnetic recording medium and a longitudinal end of the magnetic recording head. When the trapezoidal main pole 10 writes a bit data on a selected track, the main pole does not affect an adjacent track even though a skew angle S is maximum. A track width is determined by a width of a first side 10b of the main pole 10 corresponding to a long side of a trapezoidal cross section. Specifically, when the skew angle S is 0°, a maximum track width W1 is equal to the width of the first side 10b of the trapezoidal main pole 10. Wherein, the first side 10b corresponding to a long side of the trapezoid is in parallel with a second side 10a corresponding to a short side.
FIG. 2 is a cross-sectional view illustrating a laminated structure of a conventional magnetic recording head. FIG. 2 shows a longitudinal end of the magnetic recording head facing a magnetic recording medium. The magnetic recording head includes a first insulating layer 21, a second insulating layer 22, a third insulating layer 23, and a return pole layer 30. The second insulating layer 22 is formed with a slit having a trapezoidal cross section. The slit is filled with a magnetic material to form a trapezoidal main pole 10.
FIGS. 3A through 3D are cross-sectional views illustrating a method of manufacturing the conventional magnetic recording head. First, as shown in FIG. 3A, the first insulating layer 21 and a main pole layer 10′ are sequentially deposited, and a photoresist pattern 80 is formed on the main pole layer 10′. The photoresist pattern 80 is a line pattern having a desired width. A minimum value of the width of the photoresist pattern is determined by a photolithography technique to pattern the photoresist.
Next, as shown in FIG. 3B, the main pole layer 10′ is isotropically etched until the first insulating layer 21 is exposed. Hence, the trapezoidal main pole 10 is formed under the photoresist pattern 80. At this time, the trapezoidal main pole 10 has a width of a long side that is equal to that of the photoresist pattern 80.
Next, as shown in FIG. 3C, the second insulating layer 22 is formed on the first insulating layer 21. The insulating material is deposited on the entire surface of the first insulating layer until both sides of the main pole 10 are buried. The insulating material deposited on an upper portion of the trapezoidal main pole 10 may be removed together with the photoresist pattern through a lift-off technique. Alternatively, the photoresist pattern is removed by a stripper, and then, after the insulating material is deposited on the entire surface, the insulating material covering the upper portion of the main pole 10 is polished. And, as shown in FIG. 3D, the third insulating layer 23 is formed on the main pole 10 and the second insulating layer 22, and the return pole layer 30 of the magnetic material is formed on the third insulating layer 23.
The width of the photoresist pattern 80 which can be formed by a conventional photolithographic equipment is about 100 nm at least. As described above, the width W1 of the photoresist pattern 80 is equal to the width of the first side 10b of the trapezoidal main pole 10. This means that the magnetic recording medium with the conventional laminated structure has a limitation that the minimum value of the track width is about 100 nm.
In order to more increase the recording density of the magnetic recording medium, there is a demand for a new structure that can reduce a width of a trapezoidal main pole using an existing process equipment.